Experimental study of fluxon dynamics in a potential well

Dynamics of a single fluxon in an annular Josephson junction is studied in the presence of an externally applied magnetic field H. Due to the interaction of the fluxon with the radial field component, the fluxon moves in a potential well which height is proportional to H. Several spectacular features of fluxon dynamics analogous to the motion of a particle in a washboard potential are clearly observed experimentally. Periodic revolutions of the fluxon in the junction lead to a potential induced emission of plasma waves. These waves are indicated by a resonance at a certain fluxon velocity which depends on the junction length. Good agreement between experiment, theoretical model and numerical simulations is found.     

Effect of Ammonia on the Gas-Phase Hydration of the Common Atmospheric Ion HSO4?

Hydration directly affects the mobility, thermodynamic properties, lifetime and nucleation rates of atmospheric ions. In the present study, the role of ammonia on the formation of hydrogen bonded complexes of the common atmospheric hydrogensulfate (HSO₄⁻) ion with water has been investigated using the Density Functional Theory (DFT). Our findings rule out the stabilizing effect of ammonia on the formation of negatively charged cluster hydrates and show clearly that the conventional (classical) treatment of ionic clusters as presumably more stable compared to neutrals may not be applicable to pre-nucleation clusters. These considerations lead us to conclude that not only quantitative but also qualitative assessment of the relative thermodynamic stability of atmospheric clusters requires a quantum-chemical treatment.     

Early Lipid Raft-Related Changes: Interplay between Unilateral Denervation and Hindlimb Suspension

Muscle disuse and denervation leads to muscle atrophy, but underlying mechanisms can be different. Previously, we have found ceramide (Cer) accumulation and lipid raft disruption after acute hindlimb suspension (HS), a model of muscle disuse. Herein, using biochemical and fluorescent approaches the influence of unilateral denervation itself and in combination with short-term HS on membrane-related parameters of rat soleus muscle was studied. Denervation increased immunoexpression of sphingomyelinase and Cer in plasmalemmal regions, but decreased Cer content in the raft fraction and enhanced lipid raft integrity. Preliminary denervation suppressed (1) HS-induced Cer accumulation in plasmalemmal regions, shown for both nonraft and raft-fractions; (2) HS-mediated decrease in lipid raft integrity. Similar to denervation, inhibition of the sciatic nerve afferents with capsaicin itself increased Cer plasmalemmal immunoexpression, but attenuated the membrane-related effects of HS. Finally, both denervation and capsaicin treatment increased immunoexpression of proapoptotic protein Bax and inhibited HS-driven increase in antiapoptotic protein Bcl-2. Thus, denervation can increase lipid raft formation and attenuate HS-induced alterations probably due to decrease of Cer levels in the raft fraction. The effects of denervation could be at least partially caused by the loss of afferentation. The study points to the importance of motor and afferent inputs in control of Cer distribution and thereby stability of lipid rafts in the junctional and extrajunctional membranes of the muscle.     

Numerical characterization and experimental verification of an in-plane MEMS-actuator with thin-film aluminum heater

In this paper, a novel concept of a thermo-mechanical MEMS actuator using aluminum thin-film heaters on a thermal oxide for electrical insulation is presented. The actuator is part of an universal tensile testing platform for thermo-mechanical material characterization of one dimensional materials on a micro- and nano-scopic scale under different environmental conditions, as varying temperatures, pressure, moisture or even vacuum and is realised in BDRIE technology. It is shown, that the actuator concept fulfills the requirements for the use in a tensile loading stage along with heterogeneously integrated nanofunctional elements, following a specimen centered approach in line with bottom-up self-assembly processes. Simulation and experiment agree very well in the thermal and mechanical domain and allow subsequent optimisation of the actuator performance.     

Prediction of rubber stability by accelerated aging test modeling

This study was devoted to the prediction of polymer material aging. The prediction of the shelf time of tire rubber is used as an example in this article. The main steps of the whole procedure are described. They are the design of the experiment, accelerated aging testing, the construction of a multiresponse mathematical model and parameter estimation, and the extrapolation of the model in real‐life settings. The main pitfalls were deduced, and techniques to overcome these pitfalls are described. Novel methods of data modeling, such as evolutionary design of experiment and successive Bayesian estimation, were used. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1275–1284, 2005     

Synthesis of amphiphilic (meth)acrylates with oligo(ethylene glycol) and (or) oligo(propylene glycol) blocks by the esterification of (meth)acrylic acid

Thermoresponsive PEG-based (PEG stands polyethylene glycol) polymers are unique for use in medicine because of their low toxicity, good biocompatibility and biodegradability, but usually more hydrophobic and more toxic comonomers are used to adjust lower critical solution temperature (LCST). A convenient way to overcome this problem and to finely tune LCST is to use alkoxy oligo(ethylene glycol)- or alkoxy oligo(propylene glycol) (meth)acrylates as starting comonomers. Here we report on the conditions for the simple and affordable synthesis of methoxy oligo(propylene glycol) (meth)acrylate- and methoxy oligo(propylene glycol)-block-oligo(ethylene glycol) (meth)acrylate-based macromonomers with high yields (80%–98.7%) by the acid-catalyzed esterification of (meth)acrylic acid with alkoxy oligo(alkylene glycols) containing oligo(ethylene glycol) (OEG) and/or oligo(propylene glycol) (OPG) blocks. p-Toluene sulphonic acid (pTSA), alkyl(C₁₂–C₁₄)benzene sulfonic acid (ABSA) and H₂SO₄ were used as catalysts. It has been shown that pTSA and ABSA are practically the same in catalytic activity and are superior to sulfuric acid. The reaction orders with respect to catalyst was found to be close to 1 in all cases. It has been shown that the reaction is actually insensitive to the lengths of OEG and OPG blocks, as well as to the structure of the terminal alkyl group, while the esterification of acrylic acid (AA) proceeds much faster compared to methacrylic acid (MAA) one under the same conditions. The influence of temperature on the equilibrium conversions of alcohols was determined, which were found to be 89%–93% for the esterification of AA and 61%–86% for MAA in the temperature range of 60–120°C. A further increase in conversion was achieved by introducing an azeotropic agent (toluene), its optimal concentration was found to be 10%–15%.     

Selecting a Cost-Effective Test Case Prioritization Technique

Regression testing is an expensive testing process used to validate modified software and detect whether new faults have been introduced into previously tested code. To reduce the cost of regression testing, software testers may prioritize their test cases so that those which are more important, by some measure, are run earlier in the regression testing process. One goal of prioritization is to increase a test suite's rate of fault detection. Previous empirical studies have shown that several prioritization techniques can significantly improve rate of fault detection, but these studies have also shown that the effectiveness of these techniques varies considerably across various attributes of the program, test suites, and modifications being considered. This variation makes it difficult for a practitioner to choose an appropriate prioritization technique for a given testing scenario. To address this problem, we analyze the fault detection rates that result from applying several different prioritization techniques to several programs and modified versions. The results of our analyses provide insights into which types of prioritization techniques are and are not appropriate under specific testing scenarios, and the conditions under which they are or are not appropriate. Our analysis approach can also be used by other researchers or practitioners to determine the prioritization techniques appropriate to other workloads.